Anthrax Inhibitor May Counteract Toxin

Researchers from Rensselaer and the University of Toronto have designed a nanoscale assembly of molecules that successfully counteracts and inhibits anthrax toxin in animal and laboratory experiments. The novel approach used to neutralize anthrax toxin could be applied in designing potent therapeutics for a variety of pathogens and toxins, including influenza and HIV, according to the researchers.

Anthrax toxin, secreted by the anthrax bacterium, is made of proteins and toxic enzymes that bind together to inflict damage on a host organism. The inhibitor works by preventing the assembly of toxic enzyme components, thereby blocking the formation of fully assembled anthrax toxin and neutralizing its activity.

“Our eventual goal is to use the inhibitor as a human therapeutic for anthrax exposure, one that can stop the toxin from functioning inside the body,” says Ravi Kane, the Merck Associate Professor of Chemical and Biological Engineering at Rensselaer and a principal investigator of the project. “Combining the inhibitor with antibiotic therapy may increase the likelihood of survival for an infected person.”

The 2001 intentional release of anthrax spores via postal mail in the United States led to increased research on possible therapeutics and vaccines to treat toxins that could be used as biological weapons. The current treatment for anthrax exposure is antibiotics, but inhalation anthrax still has a fatality rate of 75 percent even after antibiotics are given, according to the Centers for Disease Control and Prevention. Antibiotics slow the progression of infection by targeting the bacteria, but do not counter the advanced destructive effects of anthrax toxin in the body.

Anthrax toxin is a polyvalent protein complex in that it displays multiple copies of identical binding surfaces on the same structure. The inhibitor designed by the Rensselaer-Toronto team also is polyvalent and recognizes these surface patterns on the anthrax toxin molecular structure, allowing it to bind at multiple sites and become four orders of magnitude more potent than an inhibitor that binds to a single site.